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Groups > sci.electronics.design > #446378 > unrolled thread
| Started by | Pimpom <pimpom@invalid.com> |
|---|---|
| First post | 2017-02-06 11:22 +0530 |
| Last post | 2017-02-09 04:57 -0500 |
| Articles | 20 on this page of 119 — 31 participants |
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OT: Current standard for watch precision Pimpom <pimpom@invalid.com> - 2017-02-06 11:22 +0530
Re: OT: Current standard for watch precision Phil Allison <pallison49@gmail.com> - 2017-02-05 22:13 -0800
Re: OT: Current standard for watch precision Pimpom <Pimpom@invalid.com> - 2017-02-06 17:15 +0530
Re: OT: Current standard for watch precision Phil Allison <pallison49@gmail.com> - 2017-02-06 05:11 -0800
Re: OT: Current standard for watch precision Pimpom <Pimpom@invalid.com> - 2017-02-06 19:30 +0530
Re: OT: Current standard for watch precision Phil Allison <pallison49@gmail.com> - 2017-02-06 06:33 -0800
Re: OT: Current standard for watch precision nub12 <nub12@null.com> - 2017-02-07 07:57 +0800
Re: OT: Current standard for watch precision Robert Baer <robertbaer@localnet.com> - 2017-02-08 20:06 -0800
Re: OT: Current standard for watch precision Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2017-02-06 20:16 +0200
Re: OT: Current standard for watch precision Pimpom <Pimpom@invalid.com> - 2017-02-07 00:12 +0530
Re: OT: Current standard for watch precision Don Y <blockedofcourse@foo.invalid> - 2017-02-06 11:58 -0700
Re: OT: Current standard for watch precision Jasen Betts <jasen@xnet.co.nz> - 2017-02-07 05:50 +0000
Re: OT: Current standard for watch precision rickman <gnuarm@gmail.com> - 2017-02-07 02:43 -0500
Re: OT: Current standard for watch precision Pimpom <Pimpom@invalid.com> - 2017-02-07 14:53 +0530
Re: OT: Current standard for watch precision krw@notreal.com - 2017-02-07 12:32 -0500
Re: OT: Current standard for watch precision Phil Allison <pallison49@gmail.com> - 2017-02-07 02:33 -0800
Re: OT: Current standard for watch precision upsidedown@downunder.com - 2017-02-07 17:56 +0200
Re: OT: Current standard for watch precision rickman <gnuarm@gmail.com> - 2017-02-07 17:32 -0500
Re: OT: Current standard for watch precision Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-02-07 14:52 -0800
Re: OT: Current standard for watch precision upsidedown@downunder.com - 2017-02-08 10:25 +0200
Re: OT: Current standard for watch precision rickman <gnuarm@gmail.com> - 2017-02-08 03:37 -0500
Re: OT: Current standard for watch precision Martin Brown <|||newspam|||@nezumi.demon.co.uk> - 2017-02-08 09:01 +0000
Re: OT: Current standard for watch precision rickman <gnuarm@gmail.com> - 2017-02-08 05:24 -0500
Re: OT: Current standard for watch precision Jeff Liebermann <jeffl@cruzio.com> - 2017-02-08 09:08 -0800
Re: OT: Current standard for watch precision rickman <gnuarm@gmail.com> - 2017-02-08 16:04 -0500
Re: OT: Current standard for watch precision Clifford Heath <no.spam@please.net> - 2017-02-09 08:12 +1100
Re: OT: Current standard for watch precision rickman <gnuarm@gmail.com> - 2017-02-08 17:28 -0500
Re: OT: Current standard for watch precision pcdhobbs@gmail.com - 2017-02-08 16:19 -0800
Re: OT: Current standard for watch precision rickman <gnuarm@gmail.com> - 2017-02-09 00:36 -0500
Re: OT: Current standard for watch precision rickman <gnuarm@gmail.com> - 2017-02-09 00:38 -0500
Re: OT: Current standard for watch precision Clifford Heath <no.spam@please.net> - 2017-02-09 18:39 +1100
Re: OT: Current standard for watch precision rickman <gnuarm@gmail.com> - 2017-02-09 04:16 -0500
Re: OT: Current standard for watch precision Martin Brown <|||newspam|||@nezumi.demon.co.uk> - 2017-02-09 09:46 +0000
Re: OT: Current standard for watch precision rickman <gnuarm@gmail.com> - 2017-02-09 05:03 -0500
Re: OT: Current standard for watch precision Jeroen Belleman <jeroen@nospam.please> - 2017-02-09 11:45 +0100
Re: OT: Current standard for watch precision rickman <gnuarm@gmail.com> - 2017-02-09 07:12 -0500
Re: OT: Current standard for watch precision Jeroen Belleman <jeroen@nospam.please> - 2017-02-09 13:31 +0100
Re: OT: Current standard for watch precision Martin Brown <|||newspam|||@nezumi.demon.co.uk> - 2017-02-09 12:14 +0000
Re: OT: Current standard for watch precision rickman <gnuarm@gmail.com> - 2017-02-09 07:25 -0500
Re: OT: Current standard for watch precision Martin Brown <|||newspam|||@nezumi.demon.co.uk> - 2017-02-10 09:17 +0000
Re: OT: Current standard for watch precision Jeroen Belleman <jeroen@nospam.please> - 2017-02-10 10:45 +0100
Re: OT: Current standard for watch precision rickman <gnuarm@gmail.com> - 2017-02-10 21:56 -0500
Re: OT: Current standard for watch precision Jasen Betts <jasen@xnet.co.nz> - 2017-02-11 02:06 +0000
Re: OT: Current standard for watch precision krw@notreal.com - 2017-02-10 22:24 -0500
Re: OT: Current standard for watch precision Jasen Betts <jasen@xnet.co.nz> - 2017-02-11 01:54 +0000
Re: OT: Current standard for watch precision Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-02-10 18:10 -0800
Re: OT: Current standard for watch precision Cursitor Doom <curd@notformail.com> - 2017-02-08 23:34 +0000
Re: OT: Current standard for watch precision Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-02-08 15:49 -0800
Re: OT: Current standard for watch precision pcdhobbs@gmail.com - 2017-02-08 15:55 -0800
Re: OT: Current standard for watch precision Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-02-08 16:08 -0800
Re: OT: Current standard for watch precision Ralph Barone <ralph@invalid.com> - 2017-02-09 03:24 +0000
Re: OT: Current standard for watch precision Jeff Liebermann <jeffl@cruzio.com> - 2017-02-08 20:34 -0800
Re: OT: Current standard for watch precision Tim Wescott <tim@seemywebsite.com> - 2017-02-08 23:26 -0600
Re: OT: Current standard for watch precision Jeff Liebermann <jeffl@cruzio.com> - 2017-02-08 23:28 -0800
Re: OT: Current standard for watch precision Spehro Pefhany <speffSNIP@interlogDOTyou.knowwhat> - 2017-02-09 00:48 -0500
Re: OT: Current standard for watch precision George Herold <gherold@teachspin.com> - 2017-02-09 06:52 -0800
Re: OT: Current standard for watch precision krw@notreal.com - 2017-02-09 20:37 -0500
Re: OT: Current standard for watch precision Cursitor Doom <curd@notformail.com> - 2017-02-10 17:11 +0000
Re: OT: Current standard for watch precision upsidedown@downunder.com - 2017-02-09 23:13 +0200
Re: OT: Current standard for watch precision krw@notreal.com - 2017-02-08 20:17 -0500
Re: OT: Current standard for watch precision Jeff Liebermann <jeffl@cruzio.com> - 2017-02-08 19:29 -0800
Re: OT: Current standard for watch precision Jeff Liebermann <jeffl@cruzio.com> - 2017-02-08 20:16 -0800
Re: OT: Current standard for watch precision Martin Brown <|||newspam|||@nezumi.demon.co.uk> - 2017-02-08 17:13 +0000
Re: OT: Current standard for watch precision kevin93 <kevin@whitedigs.com> - 2017-02-08 12:54 -0800
Re: OT: Current standard for watch precision krw@notreal.com - 2017-02-08 12:35 -0500
Re: OT: Current standard for watch precision Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-02-08 09:50 -0800
Re: OT: Current standard for watch precision krw@notreal.com - 2017-02-08 13:14 -0500
Re: OT: Current standard for watch precision Jeff Liebermann <jeffl@cruzio.com> - 2017-02-08 11:35 -0800
Re: OT: Current standard for watch precision upsidedown@downunder.com - 2017-02-08 23:16 +0200
Re: OT: Current standard for watch precision Jeroen Belleman <jeroen@nospam.please> - 2017-02-09 09:59 +0100
Re: OT: Current standard for watch precision Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-02-08 09:41 -0800
Re: OT: Current standard for watch precision krw@notreal.com - 2017-02-08 13:15 -0500
Re: OT: Current standard for watch precision Jasen Betts <jasen@xnet.co.nz> - 2017-02-11 01:46 +0000
Re: OT: Current standard for watch precision rickman <gnuarm@gmail.com> - 2017-02-10 22:12 -0500
Re: OT: Current standard for watch precision Jeff Liebermann <jeffl@cruzio.com> - 2017-02-09 15:25 -0800
Re: OT: Current standard for watch precision Clifford Heath <no.spam@please.net> - 2017-02-10 10:38 +1100
Re: OT: Current standard for watch precision bill.sloman@ieee.org - 2017-02-09 17:42 -0800
Re: OT: Current standard for watch precision Jeroen Belleman <jeroen@nospam.please> - 2017-02-08 11:01 +0100
Re: OT: Current standard for watch precision Jasen Betts <jasen@xnet.co.nz> - 2017-02-11 04:06 +0000
Re: OT: Current standard for watch precision krw@notreal.com - 2017-02-07 21:02 -0500
Re: OT: Current standard for watch precision Jeff Liebermann <jeffl@cruzio.com> - 2017-02-07 10:24 -0800
Re: OT: Current standard for watch precision Jeff Liebermann <jeffl@cruzio.com> - 2017-02-07 10:48 -0800
Re: OT: Current standard for watch precision George Herold <gherold@teachspin.com> - 2017-02-07 11:12 -0800
Re: OT: Current standard for watch precision Mikko OH2HVJ <mikko.syrjalahti@nospam.fi> - 2017-02-08 09:33 +0200
Re: OT: Current standard for watch precision George Herold <gherold@teachspin.com> - 2017-02-08 06:31 -0800
Re: OT: Current standard for watch precision Martin Brown <|||newspam|||@nezumi.demon.co.uk> - 2017-02-07 09:58 +0000
Re: OT: Current standard for watch precision Robert Baer <robertbaer@localnet.com> - 2017-02-08 20:00 -0800
Re: OT: Current standard for watch precision Jeff Liebermann <jeffl@cruzio.com> - 2017-02-05 23:01 -0800
Re: OT: Current standard for watch precision mike <ham789@netzero.net> - 2017-02-06 03:21 -0800
Re: OT: Current standard for watch precision Pimpom <Pimpom@invalid.com> - 2017-02-06 17:25 +0530
Re: Current standard for watch precision "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-02-06 06:57 -0600
Re: Current standard for watch precision Pimpom <Pimpom@invalid.com> - 2017-02-06 19:10 +0530
Re: Current standard for watch precision "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-02-06 08:13 -0600
Re: Current standard for watch precision Pimpom <Pimpom@invalid.com> - 2017-02-06 21:04 +0530
Re: Current standard for watch precision Spehro Pefhany <speffSNIP@interlogDOTyou.knowwhat> - 2017-02-06 09:30 -0500
Re: Current standard for watch precision George Herold <gherold@teachspin.com> - 2017-02-06 06:56 -0800
Re: Current standard for watch precision Robert Baer <robertbaer@localnet.com> - 2017-02-08 20:11 -0800
Re: Current standard for watch precision Don Y <blockedofcourse@foo.invalid> - 2017-02-06 12:04 -0700
Re: Current standard for watch precision Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-06 14:58 -0700
Re: Current standard for watch precision Don Y <blockedofcourse@foo.invalid> - 2017-02-06 15:21 -0700
Re: Current standard for watch precision Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-06 16:06 -0700
Re: Current standard for watch precision Don Y <blockedofcourse@foo.invalid> - 2017-02-06 17:19 -0700
Re: Current standard for watch precision Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-06 17:52 -0700
Re: Current standard for watch precision Don Y <blockedofcourse@foo.invalid> - 2017-02-06 17:55 -0700
Re: Current standard for watch precision krw@notreal.com - 2017-02-06 21:44 -0500
Re: Current standard for watch precision Robert Baer <robertbaer@localnet.com> - 2017-02-08 20:04 -0800
Re: OT: Current standard for watch precision Spehro Pefhany <speffSNIP@interlogDOTyou.knowwhat> - 2017-02-06 09:06 -0500
Re: OT: Current standard for watch precision Pimpom <Pimpom@invalid.com> - 2017-02-06 21:04 +0530
Re: OT: Current standard for watch precision TTman <pcw1.cad@ntlworld.com> - 2017-02-06 14:31 +0000
Re: OT: Current standard for watch precision Clifford Heath <no.spam@please.net> - 2017-02-07 08:54 +1100
Re: OT: Current standard for watch precision Tim Wescott <seemywebsite@myfooter.really> - 2017-02-06 17:33 -0600
Re: OT: Current standard for watch precision krw@notreal.com - 2017-02-06 21:23 -0500
Re: OT: Current standard for watch precision prairiesky <outgoing.server@mozilla.com> - 2017-02-06 23:00 -0800
Re: OT: Current standard for watch precision Cursitor Doom <curd@notformail.com> - 2017-02-07 18:29 +0000
Re: OT: Current standard for watch precision Robert Baer <robertbaer@localnet.com> - 2017-02-08 19:59 -0800
Re: OT: Current standard for watch precision rickman <gnuarm@gmail.com> - 2017-02-09 00:48 -0500
Re: OT: Current standard for watch precision Tim Wescott <tim@seemywebsite.com> - 2017-02-08 23:54 -0600
Re: OT: Current standard for watch precision Tim Wescott <tim@seemywebsite.com> - 2017-02-09 00:00 -0600
Re: OT: Current standard for watch precision rickman <gnuarm@gmail.com> - 2017-02-09 04:57 -0500
Page 4 of 6 — ← Prev page 1 2 3 [4] 5 6 Next page →
| From | Jeff Liebermann <jeffl@cruzio.com> |
|---|---|
| Date | 2017-02-08 19:29 -0800 |
| Message-ID | <qnnn9c5nhkmmk3514pofkumovl4pee6m6a@4ax.com> |
| In reply to | #446857 |
On Wed, 8 Feb 2017 16:04:30 -0500, rickman <gnuarm@gmail.com> wrote: >Thanks for all the links, but they don't actually explain the mechanism >for how the various generators are adjusted to maintain the grid >frequency. I didn't find that either but my guess(tm) is that with steam, you just adjust the steam pressure to slow down or speed up the turbine. Water is much the same by controlling the inflow. Big solar runs on DC to AC inverters, which should be easy. Grid tied small solar relies on the users solar controllers, which I'm told is self-synchronizing somehow in the controller. >Someone else indicated in Europe there is a central point of >measurement and once a day they send out orders to plant operators to >adjust some control that causes the generator to exert force on the >network. I suppose that creates an individually small, but in aggregate >large force to drive the grid frequency. But that has to be separate >from adjusting the generators for the varying loads. Long ago, before the invention of terrorism, I got a tour of the SCE control room in Smog Angeles. On the wall were two analog clocks. One was driven presumably by a stabilized crystal oscillator. The other ran off the local grid. They were a few seconds different. The tour guide mumbled something about adjusting them to be the same twice per day. Sorry but I don't believer she explained how this was done or exactly when. There's quite a bit on synchronizing generators on various YouTube videos: <https://www.youtube.com/results?search_query=synchronizing+ac+generators> Apparently, at utility scale, it's NOT an simple procedure: <https://www.youtube.com/watch?v=Zw39gxIqfVU> (5:44) The operators were looking for turbine vibrations by hand. -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
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| From | Jeff Liebermann <jeffl@cruzio.com> |
|---|---|
| Date | 2017-02-08 20:16 -0800 |
| Message-ID | <ulqn9cpudkb60vinuf7nq1k7rkjmq3t8lg@4ax.com> |
| In reply to | #446954 |
On Wed, 08 Feb 2017 19:29:39 -0800, Jeff Liebermann <jeffl@cruzio.com> wrote: More (for UK): "Real Time System Frequency" <http://www2.nationalgrid.com/uk/Industry-information/electricity-transmission-operational-data/> "As the UK electricity transmission system operator, National Grid carries out residual energy balancing to ensure that in every minute, the electricity demand matches the electricity received from generators. We also take system actions to ensure that there is sufficient capacity to ensure a safe flow of electricity through the network. Often, the system frequency is used as a measure of the state of balance of the system." Yeah, that's what I thought. The system operators adjust the input power to the steam and hydro generators so that they match the instantaneous load, thus keeping the RPM and line frequency constant. Even more from the financial electric traders: "Electricity Data Summary (Europe)" <https://www.bmreports.com/bmrs/?q=eds/main> "Balancing Mechanism Reporting Service (BMRS)" <https://www.bmreports.com/bmrs/?q=help/about-us> -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
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| From | Martin Brown <|||newspam|||@nezumi.demon.co.uk> |
|---|---|
| Date | 2017-02-08 17:13 +0000 |
| Message-ID | <o7fjkc$1jpo$1@gioia.aioe.org> |
| In reply to | #446763 |
On 08/02/2017 10:24, rickman wrote: > On 2/8/2017 4:01 AM, Martin Brown wrote: >> On 08/02/2017 08:37, rickman wrote: >>> On 2/8/2017 3:25 AM, upsidedown@downunder.com wrote: >>>> On Tue, 7 Feb 2017 14:52:09 -0800 (PST), Lasse Langwadt Christensen >>>> <langwadt@fonz.dk> wrote: >>>> >>>>> on the page Jeff linked to it says they can catch up ~17 seconds a >>>>> day, >>>>> once they get 20 seconds out of sync >>>>> >>>>> and it is just country wide, the synchronous grid of Continental >>>>> Europe >>>>> 667 gigawatts in 20 some countries >>>> >>>> There are thousands of generators connected in parallel and the >>>> fluctuating frequency ensures that there are proper load sharing >>>> between generators. This method has been used for more than a century. >>> >>> So how is the average frequency maintained? What actually controls the >>> long term frequency of the grid? If it were just the load sharing >>> driving the frequency up and down as the loads and generators vary, the >>> frequency would wander with no fixed average. >> >> The long term average is very carefully maintained by running the grid >> faster usually at night to catch up when the load is lowest - a quirk >> that used to annoy astronomers back in the days when synchronous 60Hz >> motors were used on some telescope drives. If you watch the realtime >> grid frequency display at times of peak load on for example UK gridwatch >> you will see the relation between load and frequency. >> >> They try never to get more than 0.2Hz out for an extended period and >> will bring in fast generators like the pumped hydro storage and gas >> turbines if it does or typically if peak load is anticipated. >> >> http://www.gridwatch.templar.co.uk/ >> >> Big football match half time is particularly hard on the grid at this >> time of year as everyone goes to put the kettle on at once and load is >> already pretty close to the upper limit. Not much margin on UK capacity. > > Yes, but *how* do they run the grid faster or slower? Also, *who* > controls this? If the drag on the generators is more than the mechanical power going into them then the frequency is slower and conversely faster if the external load goes down. Big electrolytic cells for making sodium and aluminium are used as the ultimate load balancing tools since they can be switched in and out very fast provided they are active. You can't drop them off for too long or bad things happen! There is speculation in the UK technical community that the government is bribing industry to not use power at peak evening times as the load curve appears to be different this year. In the UK a team at a now off limits central control centre balance things. They once let a live Look North(?) team film in there live and the presenter turned to the guy and said something like: Q: This meter shows current consumption? A: Yes Q: So if everybody watching switched on their kettle it would move? A: Yes Q: Switch on your kettle. Circuit breakers drop out. There was an edict to the effect never again! -- Regards, Martin Brown
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| From | kevin93 <kevin@whitedigs.com> |
|---|---|
| Date | 2017-02-08 12:54 -0800 |
| Message-ID | <75d35bbc-17a8-43ca-b3d1-5ef9b08c8697@googlegroups.com> |
| In reply to | #446799 |
On Wednesday, February 8, 2017 at 9:13:54 AM UTC-8, Martin Brown wrote: ... > Q: This meter shows current consumption? > A: Yes > Q: So if everybody watching switched on their kettle it would move? > A: Yes > Q: Switch on your kettle. > > Circuit breakers drop out. There was an edict to the effect never again! > > -- > Regards, > Martin Brown Here is a web page with the UK grid status. A few hours ago the demand was in the red region http://www.gridwatch.templar.co.uk kevin
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| From | krw@notreal.com |
|---|---|
| Date | 2017-02-08 12:35 -0500 |
| Message-ID | <oelm9c50n2rub0hquh4ieh0klcaudr7irv@4ax.com> |
| In reply to | #446763 |
On Wed, 8 Feb 2017 05:24:35 -0500, rickman <gnuarm@gmail.com> wrote: >On 2/8/2017 4:01 AM, Martin Brown wrote: >> On 08/02/2017 08:37, rickman wrote: >>> On 2/8/2017 3:25 AM, upsidedown@downunder.com wrote: >>>> On Tue, 7 Feb 2017 14:52:09 -0800 (PST), Lasse Langwadt Christensen >>>> <langwadt@fonz.dk> wrote: >>>> >>>>> on the page Jeff linked to it says they can catch up ~17 seconds a day, >>>>> once they get 20 seconds out of sync >>>>> >>>>> and it is just country wide, the synchronous grid of Continental Europe >>>>> 667 gigawatts in 20 some countries >>>> >>>> There are thousands of generators connected in parallel and the >>>> fluctuating frequency ensures that there are proper load sharing >>>> between generators. This method has been used for more than a century. >>> >>> So how is the average frequency maintained? What actually controls the >>> long term frequency of the grid? If it were just the load sharing >>> driving the frequency up and down as the loads and generators vary, the >>> frequency would wander with no fixed average. >> >> The long term average is very carefully maintained by running the grid >> faster usually at night to catch up when the load is lowest - a quirk >> that used to annoy astronomers back in the days when synchronous 60Hz >> motors were used on some telescope drives. If you watch the realtime >> grid frequency display at times of peak load on for example UK gridwatch >> you will see the relation between load and frequency. >> >> They try never to get more than 0.2Hz out for an extended period and >> will bring in fast generators like the pumped hydro storage and gas >> turbines if it does or typically if peak load is anticipated. >> >> http://www.gridwatch.templar.co.uk/ >> >> Big football match half time is particularly hard on the grid at this >> time of year as everyone goes to put the kettle on at once and load is >> already pretty close to the upper limit. Not much margin on UK capacity. > >Yes, but *how* do they run the grid faster or slower? Also, *who* >controls this? They increase the RPM of the generators to increase the frequency (and thus the power output of that generator). The grid controllers control the grid (my brother was once in charge of his end at AEP). Some generators are used to control power factor, rather than supply power). It's a complex dance but one that goes on hour after hour. That's why solar/wind is so destabilizing. It's another set of variables that can't be controlled. The answer is to back up all that power, watt for watt, saving nothing.
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| From | Lasse Langwadt Christensen <langwadt@fonz.dk> |
|---|---|
| Date | 2017-02-08 09:50 -0800 |
| Message-ID | <c95d578c-02f4-4a35-8a83-24e0a4c08f9b@googlegroups.com> |
| In reply to | #446806 |
Den onsdag den 8. februar 2017 kl. 18.35.39 UTC+1 skrev k...@notreal.com: > On Wed, 8 Feb 2017 05:24:35 -0500, rickman <gnuarm@gmail.com> wrote: > > >On 2/8/2017 4:01 AM, Martin Brown wrote: > >> On 08/02/2017 08:37, rickman wrote: > >>> On 2/8/2017 3:25 AM, upsidedown@downunder.com wrote: > >>>> On Tue, 7 Feb 2017 14:52:09 -0800 (PST), Lasse Langwadt Christensen > >>>> <langwadt@fonz.dk> wrote: > >>>> > >>>>> on the page Jeff linked to it says they can catch up ~17 seconds a day, > >>>>> once they get 20 seconds out of sync > >>>>> > >>>>> and it is just country wide, the synchronous grid of Continental Europe > >>>>> 667 gigawatts in 20 some countries > >>>> > >>>> There are thousands of generators connected in parallel and the > >>>> fluctuating frequency ensures that there are proper load sharing > >>>> between generators. This method has been used for more than a century. > >>> > >>> So how is the average frequency maintained? What actually controls the > >>> long term frequency of the grid? If it were just the load sharing > >>> driving the frequency up and down as the loads and generators vary, the > >>> frequency would wander with no fixed average. > >> > >> The long term average is very carefully maintained by running the grid > >> faster usually at night to catch up when the load is lowest - a quirk > >> that used to annoy astronomers back in the days when synchronous 60Hz > >> motors were used on some telescope drives. If you watch the realtime > >> grid frequency display at times of peak load on for example UK gridwatch > >> you will see the relation between load and frequency. > >> > >> They try never to get more than 0.2Hz out for an extended period and > >> will bring in fast generators like the pumped hydro storage and gas > >> turbines if it does or typically if peak load is anticipated. > >> > >> http://www.gridwatch.templar.co.uk/ > >> > >> Big football match half time is particularly hard on the grid at this > >> time of year as everyone goes to put the kettle on at once and load is > >> already pretty close to the upper limit. Not much margin on UK capacity. > > > >Yes, but *how* do they run the grid faster or slower? Also, *who* > >controls this? > > They increase the RPM of the generators to increase the frequency (and > thus the power output of that generator). The grid controllers > control the grid (my brother was once in charge of his end at AEP). > Some generators are used to control power factor, rather than supply > power). It's a complex dance but one that goes on hour after hour. > That's why solar/wind is so destabilizing. It's another set of > variables that can't be controlled. The answer is to back up all that > power, watt for watt, saving nothing. I seem to remember that 20% of the US generation capacity is only used 1% of the time
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| From | krw@notreal.com |
|---|---|
| Date | 2017-02-08 13:14 -0500 |
| Message-ID | <svnm9c57vk4d2kqdgllbsfmchpt4650o9r@4ax.com> |
| In reply to | #446814 |
On Wed, 8 Feb 2017 09:50:49 -0800 (PST), Lasse Langwadt Christensen <langwadt@fonz.dk> wrote: >Den onsdag den 8. februar 2017 kl. 18.35.39 UTC+1 skrev k...@notreal.com: >> On Wed, 8 Feb 2017 05:24:35 -0500, rickman <gnuarm@gmail.com> wrote: >> >> >On 2/8/2017 4:01 AM, Martin Brown wrote: >> >> On 08/02/2017 08:37, rickman wrote: >> >>> On 2/8/2017 3:25 AM, upsidedown@downunder.com wrote: >> >>>> On Tue, 7 Feb 2017 14:52:09 -0800 (PST), Lasse Langwadt Christensen >> >>>> <langwadt@fonz.dk> wrote: >> >>>> >> >>>>> on the page Jeff linked to it says they can catch up ~17 seconds a day, >> >>>>> once they get 20 seconds out of sync >> >>>>> >> >>>>> and it is just country wide, the synchronous grid of Continental Europe >> >>>>> 667 gigawatts in 20 some countries >> >>>> >> >>>> There are thousands of generators connected in parallel and the >> >>>> fluctuating frequency ensures that there are proper load sharing >> >>>> between generators. This method has been used for more than a century. >> >>> >> >>> So how is the average frequency maintained? What actually controls the >> >>> long term frequency of the grid? If it were just the load sharing >> >>> driving the frequency up and down as the loads and generators vary, the >> >>> frequency would wander with no fixed average. >> >> >> >> The long term average is very carefully maintained by running the grid >> >> faster usually at night to catch up when the load is lowest - a quirk >> >> that used to annoy astronomers back in the days when synchronous 60Hz >> >> motors were used on some telescope drives. If you watch the realtime >> >> grid frequency display at times of peak load on for example UK gridwatch >> >> you will see the relation between load and frequency. >> >> >> >> They try never to get more than 0.2Hz out for an extended period and >> >> will bring in fast generators like the pumped hydro storage and gas >> >> turbines if it does or typically if peak load is anticipated. >> >> >> >> http://www.gridwatch.templar.co.uk/ >> >> >> >> Big football match half time is particularly hard on the grid at this >> >> time of year as everyone goes to put the kettle on at once and load is >> >> already pretty close to the upper limit. Not much margin on UK capacity. >> > >> >Yes, but *how* do they run the grid faster or slower? Also, *who* >> >controls this? >> >> They increase the RPM of the generators to increase the frequency (and >> thus the power output of that generator). The grid controllers >> control the grid (my brother was once in charge of his end at AEP). >> Some generators are used to control power factor, rather than supply >> power). It's a complex dance but one that goes on hour after hour. >> That's why solar/wind is so destabilizing. It's another set of >> variables that can't be controlled. The answer is to back up all that >> power, watt for watt, saving nothing. > >I seem to remember that 20% of the US generation capacity is only used 1% >of the time But it's not spinning reserve, as is needed for greenie power.
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| From | Jeff Liebermann <jeffl@cruzio.com> |
|---|---|
| Date | 2017-02-08 11:35 -0800 |
| Message-ID | <uurm9c518jttebapngmpfi7gb20a0rifpa@4ax.com> |
| In reply to | #446814 |
On Wed, 8 Feb 2017 09:50:49 -0800 (PST), Lasse Langwadt Christensen <langwadt@fonz.dk> wrote: >I seem to remember that 20% of the US generation capacity is only used 1% >of the time I don't understand what that means. The way I read it is that generating capacity has 20% excess capacity that is only required 1% of the time. That would be 3.65 days/year or maybe 87.6 hrs/year. Is that what it means? I like to monitor CalISO (California Independent Service Operators) graphs for demand and production. The system is quite good at having production follow demand. However the capacity graphs have been dropped from the web pile allegedly because power brokers were using it to somehow improve their speculation: <http://www.caiso.com/Pages/TodaysOutlook.aspx> Anyway, notice how well the estimated and actual demand curves track. If they miss on these, such as during a wide area power outage, the decreased load will cause the generators to spin either faster or slower, which I guess is a bad thing. Well, the excess fuel used if they guess to high, or the brown-out if they guess too low, are also bad things. So, grinding the numbers, the total capacity is 74.12 MegaWatts, while the current consumption is 27.0MW which would be: (74-27) / 74 = 64% excess capacity. -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
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| From | upsidedown@downunder.com |
|---|---|
| Date | 2017-02-08 23:16 +0200 |
| Message-ID | <6a2n9ct8ef31g3ijhhep0e6i74qj1r6efu@4ax.com> |
| In reply to | #446842 |
On Wed, 08 Feb 2017 11:35:16 -0800, Jeff Liebermann <jeffl@cruzio.com> wrote: >On Wed, 8 Feb 2017 09:50:49 -0800 (PST), Lasse Langwadt Christensen ><langwadt@fonz.dk> wrote: > >>I seem to remember that 20% of the US generation capacity is only used 1% >>of the time > >I don't understand what that means. The way I read it is that >generating capacity has 20% excess capacity that is only required 1% >of the time. That would be 3.65 days/year or maybe 87.6 hrs/year. Is >that what it means? I do not know about the US, but for a smaller country, those figures sounds reasonable. You need fast starting (usually gas) turbines in case of the largest production unit (such as the largest nuclear reactor) drops off-line. Such gas turbines might be used only 100 hours a year, which includes test starts on a weekly or monthly basis.
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| From | Jeroen Belleman <jeroen@nospam.please> |
|---|---|
| Date | 2017-02-09 09:59 +0100 |
| Message-ID | <o7hb21$5p6$1@gioia.aioe.org> |
| In reply to | #446842 |
On 2017-02-08 20:35, Jeff Liebermann wrote: > On Wed, 8 Feb 2017 09:50:49 -0800 (PST), Lasse Langwadt Christensen > <langwadt@fonz.dk> wrote: > >> I seem to remember that 20% of the US generation capacity is only used 1% >> of the time > > I don't understand what that means. The way I read it is that > generating capacity has 20% excess capacity that is only required 1% > of the time. That would be 3.65 days/year or maybe 87.6 hrs/year. Is > that what it means? > > I like to monitor CalISO (California Independent Service Operators) > graphs for demand and production. The system is quite good at having > production follow demand. However the capacity graphs have been > dropped from the web pile allegedly because power brokers were using > it to somehow improve their speculation: > <http://www.caiso.com/Pages/TodaysOutlook.aspx> > Anyway, notice how well the estimated and actual demand curves track. > If they miss on these, such as during a wide area power outage, the > decreased load will cause the generators to spin either faster or > slower, which I guess is a bad thing. Well, the excess fuel used if > they guess to high, or the brown-out if they guess too low, are also > bad things. > > So, grinding the numbers, the total capacity is 74.12 MegaWatts, while > the current consumption is 27.0MW which would be: > (74-27) / 74 = 64% excess capacity. > > Off by a factor of one thousand. It's GW, not MW. Jeroen Belleman
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| From | Lasse Langwadt Christensen <langwadt@fonz.dk> |
|---|---|
| Date | 2017-02-08 09:41 -0800 |
| Message-ID | <00ee5177-b682-4e4c-881f-8c82a889f4e9@googlegroups.com> |
| In reply to | #446763 |
Den onsdag den 8. februar 2017 kl. 11.24.39 UTC+1 skrev rickman: > On 2/8/2017 4:01 AM, Martin Brown wrote: > > On 08/02/2017 08:37, rickman wrote: > >> On 2/8/2017 3:25 AM, upsidedown@downunder.com wrote: > >>> On Tue, 7 Feb 2017 14:52:09 -0800 (PST), Lasse Langwadt Christensen > >>> <langwadt@fonz.dk> wrote: > >>> > >>>> on the page Jeff linked to it says they can catch up ~17 seconds a day, > >>>> once they get 20 seconds out of sync > >>>> > >>>> and it is just country wide, the synchronous grid of Continental Europe > >>>> 667 gigawatts in 20 some countries > >>> > >>> There are thousands of generators connected in parallel and the > >>> fluctuating frequency ensures that there are proper load sharing > >>> between generators. This method has been used for more than a century. > >> > >> So how is the average frequency maintained? What actually controls the > >> long term frequency of the grid? If it were just the load sharing > >> driving the frequency up and down as the loads and generators vary, the > >> frequency would wander with no fixed average. > > > > The long term average is very carefully maintained by running the grid > > faster usually at night to catch up when the load is lowest - a quirk > > that used to annoy astronomers back in the days when synchronous 60Hz > > motors were used on some telescope drives. If you watch the realtime > > grid frequency display at times of peak load on for example UK gridwatch > > you will see the relation between load and frequency. > > > > They try never to get more than 0.2Hz out for an extended period and > > will bring in fast generators like the pumped hydro storage and gas > > turbines if it does or typically if peak load is anticipated. > > > > http://www.gridwatch.templar.co.uk/ > > > > Big football match half time is particularly hard on the grid at this > > time of year as everyone goes to put the kettle on at once and load is > > already pretty close to the upper limit. Not much margin on UK capacity. > > Yes, but *how* do they run the grid faster or slower? Also, *who* > controls this? tell the stoker to shovel faster? ;)
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| From | krw@notreal.com |
|---|---|
| Date | 2017-02-08 13:15 -0500 |
| Message-ID | <d1om9c55g2u1uq9535iq568pkkqdv3rmqr@4ax.com> |
| In reply to | #446809 |
On Wed, 8 Feb 2017 09:41:22 -0800 (PST), Lasse Langwadt Christensen <langwadt@fonz.dk> wrote: >Den onsdag den 8. februar 2017 kl. 11.24.39 UTC+1 skrev rickman: >> On 2/8/2017 4:01 AM, Martin Brown wrote: >> > On 08/02/2017 08:37, rickman wrote: >> >> On 2/8/2017 3:25 AM, upsidedown@downunder.com wrote: >> >>> On Tue, 7 Feb 2017 14:52:09 -0800 (PST), Lasse Langwadt Christensen >> >>> <langwadt@fonz.dk> wrote: >> >>> >> >>>> on the page Jeff linked to it says they can catch up ~17 seconds a day, >> >>>> once they get 20 seconds out of sync >> >>>> >> >>>> and it is just country wide, the synchronous grid of Continental Europe >> >>>> 667 gigawatts in 20 some countries >> >>> >> >>> There are thousands of generators connected in parallel and the >> >>> fluctuating frequency ensures that there are proper load sharing >> >>> between generators. This method has been used for more than a century. >> >> >> >> So how is the average frequency maintained? What actually controls the >> >> long term frequency of the grid? If it were just the load sharing >> >> driving the frequency up and down as the loads and generators vary, the >> >> frequency would wander with no fixed average. >> > >> > The long term average is very carefully maintained by running the grid >> > faster usually at night to catch up when the load is lowest - a quirk >> > that used to annoy astronomers back in the days when synchronous 60Hz >> > motors were used on some telescope drives. If you watch the realtime >> > grid frequency display at times of peak load on for example UK gridwatch >> > you will see the relation between load and frequency. >> > >> > They try never to get more than 0.2Hz out for an extended period and >> > will bring in fast generators like the pumped hydro storage and gas >> > turbines if it does or typically if peak load is anticipated. >> > >> > http://www.gridwatch.templar.co.uk/ >> > >> > Big football match half time is particularly hard on the grid at this >> > time of year as everyone goes to put the kettle on at once and load is >> > already pretty close to the upper limit. Not much margin on UK capacity. >> >> Yes, but *how* do they run the grid faster or slower? Also, *who* >> controls this? > >tell the stoker to shovel faster? ;) > Nah, you just stick your foot in the carb. ;-)
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| From | Jasen Betts <jasen@xnet.co.nz> |
|---|---|
| Date | 2017-02-11 01:46 +0000 |
| Message-ID | <o7lqdi$fb6$1@gonzo.alcatraz> |
| In reply to | #446763 |
On 2017-02-08, rickman <gnuarm@gmail.com> wrote: > On 2/8/2017 4:01 AM, Martin Brown wrote: > > Yes, but *how* do they run the grid faster or slower? Also, *who* > controls this? > Faster by pushing harder. same as if there was only one generator. not sure who, but short-term changes are done using dispatchable generators, like hydro, gas turbines, and diesel. -- This email has not been checked by half-arsed antivirus software
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| From | rickman <gnuarm@gmail.com> |
|---|---|
| Date | 2017-02-10 22:12 -0500 |
| Message-ID | <o7lvai$eok$1@dont-email.me> |
| In reply to | #447256 |
On 2/10/2017 8:46 PM, Jasen Betts wrote: > On 2017-02-08, rickman <gnuarm@gmail.com> wrote: >> On 2/8/2017 4:01 AM, Martin Brown wrote: >> >> Yes, but *how* do they run the grid faster or slower? Also, *who* >> controls this? >> > > Faster by pushing harder. same as if there was only one generator. > > not sure who, but short-term changes are done using dispatchable > generators, like hydro, gas turbines, and diesel. Your answer is like asking the world's most powerful computer how to make money in the stock market, watching it churn for hours then spit out, "Buy low, sell high". -- Rick C
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| From | Jeff Liebermann <jeffl@cruzio.com> |
|---|---|
| Date | 2017-02-09 15:25 -0800 |
| Message-ID | <gjsp9c9gfi76uivi904lhsrflhnpec4p69@4ax.com> |
| In reply to | #446759 |
On Wed, 8 Feb 2017 09:01:21 +0000, Martin Brown <|||newspam|||@nezumi.demon.co.uk> wrote: >The long term average is very carefully maintained by running the grid >faster usually at night to catch up when the load is lowest - a quirk >that used to annoy astronomers back in the days when synchronous 60Hz >motors were used on some telescope drives. Driving a telescope with the grid frequency would still annoy the astronomers today, even if it were perfect. The electrical grid is synced to GPS time, not sidereal time where the day is 23 hrs, 56 min, and 4.1 secs long. Notice that the line frequency disturbance recorder has a GPS receiver inside: <https://en.wikipedia.org/wiki/FNET#Frequency_Disturbance_Recorder> <http://fnetpublic.utk.edu> >If you watch the realtime >grid frequency display at times of peak load on for example UK gridwatch >you will see the relation between load and frequency. > >They try never to get more than 0.2Hz out for an extended period and >will bring in fast generators like the pumped hydro storage and gas >turbines if it does or typically if peak load is anticipated. > >http://www.gridwatch.templar.co.uk/ 0.2Hz / 60Hz = 0.33% error 0.0033 * 3600 sec/hr = 12 seconds/hr error Tolerable if you define extended periods as 1 hr. World map of line frequency error: <http://powerit.utk.edu/worldmap/> (0.09Hz) The Gridwatch site shows frequency excursions of up to +/-0.5Hz. <http://www.gridwatch.templar.co.uk> >Big football match half time is particularly hard on the grid at this >time of year as everyone goes to put the kettle on at once and load is >already pretty close to the upper limit. Not much margin on UK capacity. Also allegedly hard on the plumbing when everyone recycles their beer with a flush at half time. -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
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| From | Clifford Heath <no.spam@please.net> |
|---|---|
| Date | 2017-02-10 10:38 +1100 |
| Message-ID | <589cfd77$0$43778$c3e8da3$5e5e430d@news.astraweb.com> |
| In reply to | #446759 |
On 08/02/17 20:01, Martin Brown wrote: > They ... > will bring in fast generators like the pumped hydro storage and gas > turbines if it does or typically if peak load is anticipated. Except in Australia apparently, where much of the infrastructure has been privatized... and the French owner of the peak load gas-fired plant (at Pelican Point) refuses to fire it up on a day of peak demand, because it wasn't profitable enough. <http://www.macrobusiness.com.au/2017/02/caused-sa-blackout/>
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| From | bill.sloman@ieee.org |
|---|---|
| Date | 2017-02-09 17:42 -0800 |
| Message-ID | <56a0468b-babf-42ff-bd85-965e1015c404@googlegroups.com> |
| In reply to | #447106 |
On Friday, February 10, 2017 at 10:38:35 AM UTC+11, Clifford Heath wrote: > On 08/02/17 20:01, Martin Brown wrote: > > They ... > > will bring in fast generators like the pumped hydro storage and gas > > turbines if it does or typically if peak load is anticipated. > > Except in Australia apparently, where much of the infrastructure > has been privatized... and the French owner of the peak load > gas-fired plant (at Pelican Point) refuses to fire it up on a > day of peak demand, because it wasn't profitable enough. > > <http://www.macrobusiness.com.au/2017/02/caused-sa-blackout/> And the right-wing government that did the privatising some years ago ignored the fact that their regulations weren't forcing the suppliers to do the right thing, and blamed the whole fiasco on the South Australian government's enthusiasm for renewable supplies. It was - in fact - an evening of peak demand, so the solar cells weren't delivering, and there wasn't a lot of wind. The grid regulator did get cross enough to tell Pelican Point to get fired up for today's hot weather - the owners may want to wait until they can get even more money out of their asset, but the politics of running an asset to get extortionate profits are tricky, and can lead to the asset being expropriated. -- Bill Sloman, Sydney
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| From | Jeroen Belleman <jeroen@nospam.please> |
|---|---|
| Date | 2017-02-08 11:01 +0100 |
| Message-ID | <o7eq9n$157g$1@gioia.aioe.org> |
| In reply to | #446757 |
On 2017-02-08 09:25, upsidedown@downunder.com wrote: > On Tue, 7 Feb 2017 14:52:09 -0800 (PST), Lasse Langwadt Christensen > <langwadt@fonz.dk> wrote: > >> Den tirsdag den 7. februar 2017 kl. 23.32.16 UTC+1 skrev rickman: >>> On 2/7/2017 10:56 AM, upsidedown@downunder.com wrote: >>>> On Tue, 7 Feb 2017 02:43:33 -0500, rickman <gnuarm@gmail.com> wrote: >>>> >>>>> >>>>> I also remember building a clock with a vacuum florescent display with a >>>>> trimmer. I was adjusting it by beating a 60 Hz output against the power >>>>> line. I could get it very, very close, but then ten or fifteen minutes >>>>> later it would drift again! It took me awhile before I realized that >>>>> wasn't the clock, it was the power line. lol >>>>> >>>>> Does the power line still drift like that? Is there a reason why it >>>>> would in this day with the many sources of accurate timing available? >>>>> I'd expect the many generators could do a much better job of not running >>>>> up and down in frequency so much, or is this an inherent aspect of a >>>>> widely distributed network? >>>> >>>> This is exactly how synchronous AC generators are operated. A changing >>>> load will slightly change the frequency and the primary mover (water, >>>> steam) are adjusted accordingly. The variation is small and the error >>>> in a mains synchronized clocks is usually below 10 to 15 s. During the >>>> night, the network is running slightly above nominal frequency, in >>>> order to catch up before the next morning. >>> >>> I think there is more to it than that. We aren't talking about a single >>> generator, we are dealing with a country wide network that has to stay >>> very close to in phase. I would be *very* surprised to find the grid >>> would drift by multiple seconds within a day. >> >> on the page Jeff linked to it says they can catch up ~17 seconds a day, >> once they get 20 seconds out of sync >> >> and it is just country wide, the synchronous grid of Continental Europe >> 667 gigawatts in 20 some countries > > There are thousands of generators connected in parallel and the > fluctuating frequency ensures that there are proper load sharing > between generators. This method has been used for more than a century. > > In an interconnected network of many synchronous generators, there is no way that any single generator can affect the grid frequency. All generators are necessarily running at the same frequency, and for efficiency reasons, they also all try to stay in phase. Still, the frequency of the whole network tends to drift up and down with demand. In most power plants, the mains frequency error is used as an input to regulators that control the power produced by steam or water turbines driving the generators, which collectively strive to keep the frequency constant. Small plants need not bother to do so and merely keep their power output constant and their phase synchronous. In addition, in the distribution network, there are regulators that control demand by affecting the mains voltage, by switching in or out customers that have agreed to being remotely controlled, or in extreme cases, by shedding the load of some subnets altogether. With all these coupled rotating machines, the system as a whole has a lot of inertia and the system time constant is of the order of ten seconds, give or take a factor of three. The static gain of the European network is of the order of 20GW/Hz. Typically the frequency deviation is less than 50mHz. A central authority somewhere in Switzerland (for the European network) keeps track of the overall integrated frequency error and distributes data used to change the regulator set points to keep the long-term average frequency on target. Jeroen Belleman
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| From | Jasen Betts <jasen@xnet.co.nz> |
|---|---|
| Date | 2017-02-11 04:06 +0000 |
| Message-ID | <o7m2kd$h8t$1@gonzo.alcatraz> |
| In reply to | #446760 |
On 2017-02-08, Jeroen Belleman <jeroen@nospam.please> wrote: > On 2017-02-08 09:25, upsidedown@downunder.com wrote: > > In an interconnected network of many synchronous generators, there > is no way that any single generator can affect the grid frequency. every source and load effects the frequency. a single generator cannot command the frequency, but it definately has an effect. > All generators are necessarily running at the same frequency, and > for efficiency reasons, they also all try to stay in phase. Either they're connected and in phase, not connected, or suffering catastrophic failure. > Still, the frequency of the whole network tends to drift up and > down with demand. In most power plants, the mains frequency error > is used as an input to regulators that control the power produced that, and the spot energy, and fuel prices. -- This email has not been checked by half-arsed antivirus software
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| From | krw@notreal.com |
|---|---|
| Date | 2017-02-07 21:02 -0500 |
| Message-ID | <21vk9cdvm15qcapfn4okvb6m28f0khilb7@4ax.com> |
| In reply to | #446695 |
On Tue, 7 Feb 2017 17:32:13 -0500, rickman <gnuarm@gmail.com> wrote: >On 2/7/2017 10:56 AM, upsidedown@downunder.com wrote: >> On Tue, 7 Feb 2017 02:43:33 -0500, rickman <gnuarm@gmail.com> wrote: >> >>> >>> I also remember building a clock with a vacuum florescent display with a >>> trimmer. I was adjusting it by beating a 60 Hz output against the power >>> line. I could get it very, very close, but then ten or fifteen minutes >>> later it would drift again! It took me awhile before I realized that >>> wasn't the clock, it was the power line. lol >>> >>> Does the power line still drift like that? Is there a reason why it >>> would in this day with the many sources of accurate timing available? >>> I'd expect the many generators could do a much better job of not running >>> up and down in frequency so much, or is this an inherent aspect of a >>> widely distributed network? >> >> This is exactly how synchronous AC generators are operated. A changing >> load will slightly change the frequency and the primary mover (water, >> steam) are adjusted accordingly. The variation is small and the error >> in a mains synchronized clocks is usually below 10 to 15 s. During the >> night, the network is running slightly above nominal frequency, in >> order to catch up before the next morning. > >I think there is more to it than that. We aren't talking about a single >generator, we are dealing with a country wide network that has to stay >very close to in phase. I would be *very* surprised to find the grid >would drift by multiple seconds within a day. It wouldn't be the first time you've been wrong.
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